Method for Producing Hydrocarbon Fuel Oil

ABSTRACT

To efficiently obtain a liquid fuel containing no sulfur and having good cold flow properties by hydrotreating heavy wax generated by the Fischer-Tropsch (FT) synthesis to perform cracking with the gasification rate restrained and also increase an isomerization reaction which occurs at the same time. 
     A method for producing a hydrocarbon fuel oil, in which heavy wax generated by the FT synthesis is hydrotreated with a catalyst of the platinum group using zeolite or silica-alumina as a support under specific reaction conditions corresponding to the kind of the support, thereby performing cracking and an isomerization reaction.

TECHNICAL FIELD

The present invention relates to a method for producing a hydrocarbon fuel oil or a base material thereof, particularly a fraction corresponding to kerosene and gas oil, from a paraffinic synthetic raw material generated by a reaction of carbon monoxide and hydrogen, the so-called Fischer-Tropsch (FT) synthesis.

More particularly, the invention relates to a method for producing a hydrocarbon fuel oil or a base material thereof, particularly a kerosene-gas oil-corresponding fraction, which contains no sulfur and has good cold flow properties, for example, the pour point and cloud point measured according to JIS K2269 or the coldfilter plugging point measured according to JIS K2288.

BACKGROUND ART

Crude oil-derived kerosene-gas oil distillate fractions generally contain sulfur compounds. When these oils are used as a fuel, sulfur which exists in the sulfur compounds is converted to low molecular weight sulfur compounds, and exhausted in the air. Further, in an exhaust gas treatment apparatus which is recently being introduced, when the sulfur compound exists in the fuel, there is a fear of poisoning of a catalyst used. Furthermore, aromatic compounds are contained in the crude oil-derived kerosene-gas oil distillate fractions, and it is said that these increase suspended particulate matter (PM) and nitrogen oxides (No_(x)) in the exhaust gas. Accordingly, the fuel oil is preferably one which is small in sulfur content and aromatic content.

In a product generated by the Fischer-Tropsch synthesis (hereinafter also referred to as the FT process) using a mixed gas comprising carbon monoxide and hydrogen, no sulfur compound is contained, because impurities in the mixed gas are removed. Further, the product by this FT process comprises normal paraffin as a main component, and the aromatic compounds are scarcely contained.

On the other hand, the product generated by the FT process comprises normal paraffin as a main component, and contains heavy wax in large amounts, which is solid at ordinary temperature and can not be used as a liquid fuel. For that reason, for example, when it is distilled in a cut range equivalent to that of the commercially available crude oil-derived gas oil, crystals of the wax are liable to be precipitated at low temperature. Accordingly, cold flow properties are not so good. In order to improve cold flow properties to be used as a fuel for diesel-powered vehicles, it is possible to decrease the cut temperature of distillation to lower the 90% distillation temperature measured according to JIS K2254, and the like, thereby reducing the mixing ratio of the heavy components. However, according to this, the heavy components can not be used, so that the yield of the gas oil fraction decreases.

Accordingly, a method for obtaining a fuel oil in which these fractions of products generated by the FT process which are heavy and unusable as kerosene and gas oil are effectively utilized and moreover cold flow properties are not impaired becomes necessary.

There has hitherto been known a method for obtaining a fuel oil having good cold flow properties by hydrotreating a product obtained by the FT process to perform cracking and isomerization. For example, in a method for producing a hydrocarbon fuel oil from a hydrocarbon feed raw material comprising a product oil obtained by the FT process and having a boiling point higher than the boiling point range of the hydrocarbon fuel oil, there has been known a method for producing the hydrocarbon fuel oil, particularly naphtha or a kerosene-gas oil fraction, which comprises bringing the above-mentioned hydrocarbon feed raw material into contact with a catalyst under the presence of hydrogen under elevated temperature and pressure, the catalyst containing a silica-alumina support impregnated with platinum obtained by a method comprising bringing silica-alumina into contact with a platinum salt under the presence of a liquid under acidic conditions (see patent document 1). Further, there has been known a treating method to a base oil and the like having good cold flow properties by hydrogenation and isomerization of a charged raw material produced by the FT process (see patent document 2).

Patent Document 1: JP-A-5-302088

Patent Document 2: JP-T-8-511302 (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application.)

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

As described above, there has hitherto been proposed the method for obtaining the fuel having good cold flow properties by hydrotreating the heavy wax produced by the FT process to perform cracking and isomerization. However, the conventional hydrogenation treatment generates light gas, which reduces the yield of valuable distillates. Further, some kinds of catalysts decompose, but isomerization does not occur so much, resulting in failure to obtain a fuel having good cold flow properties.

Under such an actual situation as described above, an object of the invention is to efficiently obtain a liquid fuel containing no sulfur and having good cold flow properties by hydrotreating heavy wax generated by the FT process to perform cracking with the gasification rate restrained and to also increase an isomerization reaction which occurs at the same time.

Means for Solving the Problems

The present inventors have made a series of studies in order to achieve the above-mentioned object. As a result, it has been found that when heavy wax generated by the FT process is hydrotreated with a catalyst of the platinum group using a specific support under specific reaction conditions corresponding to the kind of support used, thereby performing cracking and isomerization reactions, the gasification rate is restrained to increase the yield of a kerosene-gas oil fraction, resulting in improvement in cold flow properties of these fractions. Thus, the invention has been completed.

That is to say, in order to achieve the above-mentioned object, the invention provides the following methods for producing a hydrocarbon fuel oil.

(1) A method for producing a hydrocarbon fuel oil, wherein wax generated by the Fischer-Tropsch synthesis and containing 50% or more by mass of normal paraffin having 7 to 100 carbon number is cracked and isomerized at a gasification rate of less than 10% by mass to an isoparaffin ratio in a fraction with 9 to 21 carbon number of 70% or more by mass, using a catalyst in which at least one kind of platinum group metal is contained on a support comprising zeolite as a main component in an amount of 0.01 to 10% by mass, in terms of metal, on a catalyst basis, at a hydrogen partial pressure of 2 to 20 MPa, at a temperature of 200 to 320° C., at a liquid hourly space velocity of 0.1 to 2 h⁻¹ and at a hydrogen/oil ratio of 100 to 2000 L/L (hereinafter referred to as the “first method” of the invention).

(2) A method for producing a hydrocarbon fuel oil, wherein wax generated by the Fischer-Tropsch synthesis and containing 50% or more by mass of normal paraffin having 7 to 100 carbon number is cracked and isomerized at a gasification rate of less than 10% by mass to an isoparaffin ratio in a fraction with 9 to 21 carbon number of 70% or more by mass, using a catalyst in which at least one kind of platinum group metal is contained on a support comprising silica-alumina as a main component in an amount of 0.01 to 10% by mass in terms of metal on a catalyst basis, at a hydrogen partial pressure of 2 to 20 MPa, at a temperature of 350 to 400° C., at a liquid hourly space velocity of 0.1 to 2 h⁻¹ and at a hydrogen/oil ratio of 100 to 2000 L/L (hereinafter referred to as the “second method” of the invention).

Effect of the Invention

According to the invention, a liquid fuel containing no sulfur and having good cold flow properties can be efficiently obtained by hydrotreating heavy wax generated by the FT process to perform cracking with the gasification rate restrained and to also increase an isomerization reaction which occurs at the same time.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a graph showing the normal paraffin contents corresponding to the carbon numbers of raw material waxes used in examples and comparative examples.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention is described in detail below.

As described above, the invention is characterized in that heavy wax generated by the FT process is hydrotreated with a catalyst of the platinum group using a specific support under specific reaction conditions corresponding to the kind of support used.

The catalyst used in the invention is a catalyst of the platinum group in which at least one kind of platinum group metal is contained on a support. The platinum group metals include platinum, palladium, ruthenium and rhodium, and platinum is particularly preferred. These can be used either alone or as a combination of two or more thereof. The content of the platinum group metal in the catalyst used in the invention is from 0.01 to 10% by mass, in terms of metal, on a catalyst basis. However, these platinum group metals have different wax cracking rates depending on the difference in the metal species, even when they have the same content. Accordingly, in order to increase the yield of a desired distillate, it is desirable to optimize the content for each metal species within the above-mentioned content range. For example, in order to increase the yield of a kerosene-gas oil fraction having 9 to 21 carbon number when platinum is used, The content of platinum in the catalyst is preferably from 0.05 to 5% by mass, and more preferably from 0.1 to 1% by mass, in terms of metal, on a catalyst basis.

The support of the catalyst of the platinum group used in the invention is a support comprising zeolite as a main component in the first method. The zeolite may be either natural or synthetic. Examples thereof include faujasite X-type zeolite, faujasite Y-type zeolite (hereinafter referred to as “Y-type zeolite”), chabazite type zeolite, mordenite type zeolite, zeolite beta an MCM-based zeolite, ZSM-based zeolite and the like. Above all, Y-type zeolite, stabilized Y zeolite (hereinafter referred to as “USY-type zeolite”) and the like are preferred. In particular, preferred is proton type zeolite. Further, the atomic ratio (Si/Al) of silicon element to aluminum element in the zeolite is preferably about 1 or more, and furthermore, an alkali metal ion such as sodium in the zeolite is usually preferably about 0.5% or less by mass based on the zeolite, because when the content is large, catalytic activity is reduced.

In the second method, the support is a support comprising silica-alumina as a main component. Although the weight ratio of silica and alumina is not particularly limited, the silica/alumina weight ratio in the support is desirably 1.5 or more, for accelerating the isomerization reaction to obtain the fuel oil having a high isoparaffin ratio and good cold flow properties.

In the invention, different reaction conditions are employed depending on the kind of support in the first and second methods, as described above. However, when the reaction conditions employed are optimized, it is also possible to use another support other than the zeolite and silica-alumina.

As the above-mentioned other supports, there can be used various ones of one or more kinds selected from inorganic oxides, inorganic crystalline compounds or clay minerals.

The inorganic oxides include, for example, silica, alumina, boria, magnesia, titania, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, silica-boria, alumina-zirconia, alumina-titania, alumina-boria, alumina-chromina, titania-zirconia, silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia and silica-magnesia-zirconia. Above all, alumina, alumina-boria, alumina-titania and alumina-zirconia are preferred, and particularly, of the alumina, γ-alumina is preferred. Further, the inorganic crystalline compounds or the clay minerals include molecular sieves and other inorganic crystalline compounds or clay minerals such as montmorillonite, kaolin, bentonite, attapulgite, bauxite, kaolinite, nakhlite and anoxite. These can be used either alone or as a combination of two or more thereof.

The specific surface area, pore volume and mean pore diameter of the above-mentioned various supports are not particularly limited in the invention. However, in order to obtain the catalyst having excellent hydrogenation activity, the specific surface area is preferably 250 m²/g or more, the pore volume is preferably from 0.1 to 1.0 mL/g, and the mean pore diameter is preferably from 0.5 to 25 nm.

Further, in the catalyst using the silica-containing support, a support containing 20% or more by mass of silica is preferred, for accelerating the isomerization reaction to obtain the fuel oil having a high isoparaffin ratio and good cold flow properties.

A method for allowing the support to contain an active metal such as the metal of the platinum group, that is to say, a method for preparing the catalyst used in the invention, can be performed by using some known techniques.

One method thereof includes an impregnation method which allows the support to contain a solution obtained by dissolving a metal compound of the metal of the platinum group in a solvent such as water, alcohol, ether or ketone, by one or more impregnation treatments. Drying and calcination are performed after the impregnation treatment. When the plurality of impregnation treatments are performed, drying and calcination may be performed between the respective impregnation treatments.

Another method includes a spray method which sprays a solution obtained by dissolving a metal compound of the metal of the platinum group, or a chemical vapor deposition method which allows the above-mentioned metal component to be chemically deposited.

Still another method includes a kneading method which allows a support component before molding to contain all or a part of a metal component of the metal of the platinum group, a coprecipitation method and an alkoxide method.

The physical properties such as the specific surface area and the pore volume of the catalyst prepared by the various methods as described above and used in the invention are not particularly limited in the invention. However, in order to obtain the catalyst having excellent hydrogenation activity, it is preferred that the specific surface area is 200 m²/g or more, that the pore volume is from 0.1 to 1.2 mL/g, that the mean pore diameter is from 0.5 to 25 nm, and that the pore size distribution (MPD±1.5 nm) is 70% or more.

The catalyst used in the invention can be used in powder form, in granular form, in spherical form, in pellet form, in honeycomb form or in any other form, without regard to the form and structure thereof. However, it is desirable to select the form according to the type of a reactor. When the reactor is a fixed bed, a molded article is generally used. Further, when the catalyst is molded to use, a binder of an organic or inorganic compound or the like may be used, within the range not impairing the effects of the invention.

In the invention, as reaction conditions of the cracking and isomerization reaction, under reaction conditions corresponding to the kind of support of the catalyst used are employed, in order to attain the desired object. That is to say, in the first method, the cracking and isomerization reaction are performed, taking the hydrogen partial pressure as 2 to 20 MPa, the temperature as 200 to 320° C., the liquid hourly space velocity as 0.1 to 2 h⁻¹, and the hydrogen/oil ratio as 1.00 to 2000 L/L.

Further, in the second method, the hydrogen partial pressure, the liquid hourly space velocity and the hydrogen/oil ratio are in the same range as in the first method, and the temperature is taken as 350 to 400° C.

Still further, in the case of the catalyst in which another support other than the above-mentioned zeolite and silica-alumina is used, the hydrogen partial pressure, the liquid hourly space velocity and the hydrogen/oil ratio may be generally in the same range as in the first method and the second method. However, it is desirable to select the optimum ranges, including the temperature, depending on the kind of another support used.

When the hydrogen partial pressure is less than 2 MPa, cracking activity of the wax is excessively reduced. Exceeding 20 MPa requires high-cost equipment which can withstand such a high pressure, resulting in bad economy. The hydrogen partial pressure is preferably from 2 to 10 MPa, and more preferably from 2.5 to 8 MPa.

In the case of the first method, when the temperature is less than 200° C., catalytic activity is excessively reduced. Exceeding 320° C. causes excessive progress of cracking, resulting in an increase in the gasification rate. In the case of the first method, the temperature is preferably from 235 to 320° C., and more preferably from 245 to 315° C. Further, in the case of the second method, when the temperature is less than 350° C., catalytic activity is excessively reduced. Exceeding 400° C. causes excessive progress of cracking, resulting in an increase in the gasification rate. In the case of the second method, the temperature is preferably from 355 to 390° C., and more preferably from 370 to 380° C.

When the liquid hourly space velocity is less than 0.1 h⁻¹, processing efficiency is reduced. Exceeding 2 h⁻¹ excessively shortens the contact time of the catalyst and a raw oil, resulting in failure to fully develop catalytic activity. The liquid hourly space velocity is preferably from 0.5 to 1 h⁻¹.

When the hydrogen/oil ratio is less than 100 L/L, decomposition activity of the wax is excessively reduced. Exceeding 2000 L/L causes a rise in hydrogen production cost, resulting in bad economy. The hydrogen/oil ratio is preferably from 200 to 1500 L/L, and more preferably form 300 to 1200 L/L.

An oil to be processed (raw oil) used in the invention is a wax comprising normal paraffin as a main component and containing 50% or more by mass of normal paraffin having 7 to 100 carbon number, and a liquid product (synthetic hydrocarbon oil) obtained by the FT process.

As the raw oil, for example, one obtained as a single lot may be used alone, or one obtained as a plurality of lots may be used as a mixture thereof. Further, one obtained using a definite catalyst under definite reaction conditions may be used alone, or a plurality of ones obtained using different catalysts under different reaction conditions may be used as a mixture thereof.

According to the production method of the hydrocarbon fuel oil of the invention, a kerosene-gas oil fraction having a high isoparaffin ratio and good cold flow properties can be obtained from the synthetic hydrocarbon oil obtained by the FT synthesis as described above. Commercially available kerosene-gas oil fractions are generally fractions containing 9 to 25 carbon number. However, when the kerosene-gas oil fraction is produced according to the invention, it is preferred in terms of easy prevention of the wax from precipitation that the kerosene-gas oil fraction having 9 to 21 carbon number (distillation temperature: about 150 to 350° C.) is produced.

In the invention, the raw oil obtained by the FT process (containing one having about 5 or more carbon number) may be used as it is, or a light component may be removed by distillation to use, as long as it contains normal paraffin having 7 to 100 carbon number in an amount of 50% or more by mass. Preferably, it is preferred that the light component is removed by distillation to decrease normal paraffin having a carbon number corresponding to that of the kerosene-gas oil fraction in the raw oil, particularly normal paraffin having 20 or less carbon number, preferably to 30% or less by mass, and more preferably to 10% or less by mass. That is to say, it is desirable that normal paraffin having 21 or more carbon number in the raw oil is preferably more than 70% by mass, and more preferably more than 90% by mass. This is preferred in that the light component is removed by distillation, thereby being able to prevent normal paraffin having a carbon number corresponding to that of the kerosene-gas oil fraction or a carbon number corresponding to that of a lighter fraction from being gasified to cause an increase in the gasification rate, or from remaining unisoparaffinized without cracking to cause an increase in the pour point of the fuel oil obtained.

Further, when paraffin having carbon number exceeding 100 is contained in large amounts in the raw oil, the melting point of the raw oil increases. Accordingly, clogging is liable to occur in a pump or a line for raw material supply. In order to prevent this clogging, heating at a higher temperature is required, but cost rises. Furthermore, when the raw oil containing paraffin having carbon number exceeding 100 in large amounts is intended to be cracked, it is necessary to employ severer cracking conditions. Accordingly, heat energy cost rises. Moreover, it is difficult to control the cracking under such severe conditions, and there is the possibility that a cracked component does not remain in the kerosene-gas oil fraction, resulting in excessive cracking to a lighter fraction. Accordingly, the paraffin having carbon number exceeding 100 in the raw oil is desirably the lower limit detectable with a gas chromatograph or less (less than about 0.1% by mass).

Still further, when the heavy wax used as the raw oil and generated by the FT process contains oxygen-containing compounds in the conventional hydrogenation treatment, the catalyst is poisoned. Accordingly, a treatment for previously removing the oxygen-containing compounds from the raw material is required. However, in the invention, there is no problem even when the oxygen-containing compounds are contained in the raw oil. In the invention, the raw oil may contain the oxygen-containing compounds in an amount of 0.01% or more by mass, by the oxygen mass ratio on an anhydrous basis.

In the production method of the hydrocarbon fuel oil of the invention, the content of the light normal paraffin can be restrained to suppress a gasification rate of less than 10%, preferably less than 5%, as described above.

As described above, according to the production method of the hydrocarbon fuel oil of the invention, the kerosene-gas oil fraction having a high isoparaffin ratio and good cold flow properties can be obtained. However, it is desirable that this kerosene-gas oil fraction having good cold flow properties has an isoparaffin ratio of 70% or more by mass. An isoparaffin ratio of 70% or more by mass is desirable for meeting the JIS standard of gas oil. That is to say, in order to use it as gas oil in Japan, it is necessary to meet the pour point and coldfilter plugging point specified in JIS K2204. For example, for gas oil (grade 2) used in a wide range of area, the pour point is specified as −7.5° C. or less, and the coldfilter plugging point is specified as −5° C. or less. For gas oil (special grade 1) used in a temperate region, the pour point is specified as +5° C. or less (the coldfilter plugging point is not specified). When it is used as a diesel engine fuel oil, the pour point is preferably +5° C. or less, and more preferably −7.5° C. or less, even in the temperate region.

However, in the invention, even when the isoparaffin ratio is less than 70% by mass and the pour point is higher than a desired pour point, it can be mixed with a base material more excellent in cold flow properties to adjust the pour point to the desired pour point. As the base material excellent in cold flow properties in that case, a light hydrocarbon or one containing an aromatic compound in large amounts is considered. However, when the light hydrocarbon is mixed, it is desirable to adjust so that the kinematic viscosity does not become too low. Further, when the one containing an aromatic compound in large amounts is mixed, it is desirable to adjust so that an excessive increase in suspended particulate matter (PM) or nitrogen oxides (No_(x)) is not caused, because it is said that the base material containing an aromatic compound in large amounts generally increases the PM and No_(x).

When the invention is carried out on a commercial scale, what is necessary is just to load the catalyst to a fixed bed, a moving bed or a fluidized bed in an appropriate reactor, to introduce the above-mentioned raw oil into this reactor, and to perform the treatment under the above-mentioned hydrogenation treatment conditions. Most generally, the above-mentioned catalyst is maintained as the fixed bed, and the raw oil is allowed to pass downward through the fixed bed.

In carrying out the invention on a commercial scale, a single reactor may be used, or two or more continuous reactors can also be used. The reaction is conducted in multiple stages using two or more reactors, and reactions in each stage are performed under mild reaction conditions, thereby being able to improve the yield as the whole reaction of the desired kerosene-gas oil fraction.

Further, when the single reactor is used, two or more different catalysts can also be filled in the reactor to perform the reaction. In this case, the inside of the reactor is divided into two or more layers, and the different catalysts can be dividedly filled in each layer, or the catalysts can be mixed and filled in one layer. Furthermore, when the two or more continuous reactors are used, the different catalysts can also be used in the respective reactors.

Still further, a separating apparatus is installed on the downstream side from the reactor, and heavy fractions separated can be introduced into the upstream side from the reactor to perform a hydro-cracking treatment again. For example, a hydrogenated product is separated in a distillation column, and heavy unconverted materials can be introduced into a hydro-cracking apparatus for a higher conversion to perform the hydro-cracking treatment again.

Furthermore, when the hydrogenated product is recovered, at least a part of the hydro-cracked products is separated, and then, it is treated by a single operation to produce hydrogen, thereby being also able to at least partially recover the hydrogen as a product.

EXAMPLES

The present invention will be illustrated in greater detail with reference to the following examples and comparative examples, but the invention should not be construed as being limited thereto.

Example 1

Using a catalyst of the platinum group in which platinum is contained in a silica-alumina support shown in Table 3 in an amount of 0.5% by mass, in terms of metal, on a catalyst basis, and using as a raw material wax-1 shown in Table 2 and FIG. 1, hydrotreating reaction was conducted under conditions of Table 1 at a reaction temperature of 360° C., and activity evaluation was carried out. The evaluation results are shown in Table 4.

Here, activity evaluation was carried out as follows. That is to say, raw wax was supplied to an upstanding cylindrical fixed bed flow type reactor downward from the top thereof. For the size of the reactor, the internal diameter was 12 mm (wall thickness: 3 mm), and a catalyst of 18 mL was filled. Prior to reaction evaluation, a pretreatment reduction was performed under a hydrogen flow at 300° C. for 2 hours, using a heater with which the reactor was equipped. In that case, the hydrogen flow rate is 150 mL/min, and the hydrogen partial pressure is 3.0 MPa. The reaction was conducted controlling the reaction temperature by setting of the heater, the reaction pressure with a pressure-regulating valve, and the hydrogen/oil ratio with a mass flow controller, respectively. A two-stage trap for collecting a reaction product was provided downstream from the fixed bed flow type reactor. The first stage was heated at 200° C., and the second stage was cooled with ice water. A heavy fraction and a light fraction were each collected in the respective stages.

The gasification rate, the kerosene-gas oil yield and the isoparaffin ratio in kerosene and gas oil, which are shown in Table 4, are defined as follows.

The gasification rate was defined as the percent by mass of the gaseous product collected based on the mass of the raw material supplied in the activity evaluation.

As for the kerosene-gas oil yield, first, the product collected in the activity evaluation was analyzed with gas chromatography, and the total percent by mass of materials having 9 to 21 carbon number was determined. Then, the percent by mass obtained by subtracting the gasification rate from 100% by mass was multiplied with the total percent by mass of materials having 9 to 21 carbon number, thereby defining the kerosene-gas oil yield.

The isoparaffin ratio in kerosene and gas oil was defined as the percent by mass of isoparaffin therein at the time when the materials having 9 to 21 carbon number were taken as 100% by mass with a gas chromatograph.

TABLE 1 Reaction Pressure 3 MPa Liquid hourly space 0.5 h⁻¹ velocity Hydrogen/Oil Ratio 1000 L/L Apparatus High-Pressure Fixed Bed Flow Reactor

TABLE 2 Wax-1 Wax-2 Wax-3 20 or Less Carbon number (% by mass) 3.3 33.0 0.0 21 or More Carbon number (% by mass) 96.7 67.0 100.0 Normal Paraffin Having 20 or Less Carbon 3.0 31.2 0.0 number (% by mass)

TABLE 3 USY-Type USY-Type Y-Type Silica- Support Zeolite 1 Zeolite 2 Zeolite Alumina Alumina ICP-Pt (mass %) 0.5 0.5 0.5 0.5 0.5 ICP-Al (mass %) 10 12 9 9 51 ICP-Si (mass %) 31 22 27 30 0 Supported Metal Specific Surface Area (m²/g) 0.2153 0.4104 0.4387 0.1143 1.0208 Supported Metal Particle Size (nm) 5.41 2.84 2.66 10.2 11.4 Supported Metal Dispersion Degree (%) 9.1 17.3 18.5 4.8 43.0 Catalyst BET Specific Surface Area (m²/g) 406 565 392 460 150 Catalyst Pore Radius (nm) 2.09 2.29 0.93 2.09 2.33 Catalyst Pore Volume (mL/g) 0.11 0.27 0.12 0.46 0.35 Note: In Table 3, ICP is an abbreviation of “Inductively Coupled Plasma” (emission spectrochemical analysis).

Example 2

Activity evaluation was carried out in the same manner as in Example 1 with the exception that the reaction temperature was changed to 375° C. The evaluation results are shown in Table 4.

Example 3

Using a catalyst of the platinum group in which platinum is contained in a USY type zeolite 1 support shown in Table 3 in an amount of 0.5% by mass, in terms of metal, on a catalyst basis, and using as a raw material wax-1 shown in Table 2 and FIG. 1, a hydrotreating reaction was conducted under conditions of Table 1 at a reaction temperature of 230° C., and activity evaluation was carried out. The evaluation results are shown in Table 4.

Example 4

Activity evaluation was carried out in the same manner as in Example 3 with the exception that the reaction temperature was changed to 240° C. The evaluation results are shown in Table 4.

Example 5

Activity evaluation was carried out in the same manner as in Example 3 with the exception that the reaction temperature was changed to 250° C. The evaluation results are shown in Table 4.

Example 6

Using a catalyst of the platinum group in which platinum is contained in a Y type zeolite support shown in Table 3 in an amount of 0.5% by mass, in terms of metal, on a catalyst basis, and using as a raw material wax-1 shown in Table 2 and FIG. 1, a hydrotreating reaction was conducted under conditions of Table 1 at a reaction temperature of 300° C., and activity evaluation was carried out. The evaluation results are shown in Table 4.

Example 7

Activity evaluation was carried out in the same manner as in Example 6 with the exception that the reaction temperature was changed to 310° C. The evaluation results are shown in Table 4.

Example 8

Using a catalyst of the platinum group in which platinum is contained in a USY type zeolite 2 support shown in Table 3 in an amount of 0.5% by mass, in terms of metal, on a catalyst basis, and using as a raw material wax-1 shown in Table 2 and FIG. 1, a hydrotreating reaction was conducted under conditions of Table 1 with the exception that the liquid hourly space velocity was changed to 1.0 h⁻¹ and that the hydrogen/oil ratio was changed to 500 L/L, at a reaction temperature of 220° C., and activity evaluation was carried out. The evaluation results are shown in Table 4.

Comparative Example 1

Activity evaluation was carried out in the same manner as in Example 1 with the exception that the reaction temperature was changed to 350° C. The evaluation results are shown in Table 4.

Comparative Example 2

Activity evaluation was carried out in the same manner as in Example 1 with the exception that the reaction temperature was changed to 400° C. The evaluation results are shown in Table 4.

Comparative Example 3

Activity evaluation was carried out in the same manner as in Example 1 with the exception that the reaction temperature was changed to 410° C. The evaluation results are shown in Table 4.

Comparative Example 4

Activity evaluation was carried out in the same manner as in Example 3 with the exception that the reaction temperature was changed to 260° C. The evaluation results are shown in Table 4.

Comparative Example 5

Activity evaluation was carried out in the same manner as in Example 6 with the exception that the reaction temperature was changed to 280° C. The evaluation results are shown in Table 4.

Comparative Example 6

Activity evaluation was carried out in the same manner as in Example 6 with the exception that the reaction temperature was changed to 320° C. The evaluation results are shown in Table 4.

Comparative Example 7

Using a catalyst of the platinum group in which platinum is contained in a USY type zeolite 2 support shown in Table 3 in an amount of 0.5% by mass, in terms of metal, on a catalyst basis, and using as a raw material wax-1 shown in Table 2 and FIG. 1, a hydrotreating reaction was conducted under conditions of Table 1 with the exception that the liquid hourly space velocity was changed to 1.0 h⁻¹ and that the hydrogen/oil ratio was changed to 500 L/L, at a reaction temperature of 240° C., and activity evaluation was carried out. The evaluation results are shown in Table 4.

Comparative Example 8

Activity evaluation was carried out in the same manner as in Example 8 with the exception that the raw material was changed to wax-2 shown in Table 2 and FIG. 1. The evaluation results are shown in Table 4.

Wax-2 contained normal paraffin having 21 or less carbon number in an amount exceeding 30% by mass, as found in Table 2, so that the gasification rate was high, compared to Example 8. Further, The isoparaffin ratio decreased, because normal paraffin uncracked to a kerosene-gas oil fraction having 9 to 21 carbon number remained.

Comparative Example 9

Activity evaluation was carried out in the same manner as in Comparative Example 8 with the exception that the reaction temperature was changed to 230° C. The evaluation results are shown in Table 4.

Wax-2 was used as the raw material, so that an increase of 10° C. higher than Comparative Example 8 resulted in a further increase in the gasification rate. The isoparaffin ratio in kerosene and gas oil having 9 to 21 carbon number was low.

Comparative Example 10

Using a catalyst of the platinum group in which platinum is contained in a USY type zeolite 2 support shown in Table 3 in an amount of 0.5% by mass, in terms of metal, on a catalyst basis, and using as a raw material wax-2 shown in Table 2 and FIG. 1, a hydrotreating reaction was conducted under conditions of Table 1 at a reaction temperature of 210° C., and activity evaluation was carried out. The evaluation results are shown in Table 4.

The gasification rate was equivalent to Comparative Example 8 and below 10% by mass. However, wax-2 was used as the raw material, so that the isoparaffin ratio in kerosene and gas oil was low.

TABLE 4 Yield of Kerosene- Isoparaffin Ratio in Gasification Gas oil Kerosene-Gas oil Rate Fraction Fraction % by mass % by mass % by mass Example 1 4.2 50.3 71.5 Example 2 5.3 80.3 85.8 Example 3 0.0 28.1 72.8 Example 4 1.5 41.9 87.2 Example 5 2.0 72.8 98.4 Example 6 2.4 57.0 89.8 Example 7 6.0 47.6 96.7 Example 8 7.8 35.8 74.4 Comparative 2.6 33.3 59.2 Example 1 Comparative 11.2 54.2 94.1 Example 2 Comparative 23.2 38.5 94.6 Example 3 Comparative 10.3 38.4 97.4 Example 4 Comparative 0.8 22.6 65.0 Example 5 Comparative 43.0 40.8 90.0 Example 6 Comparative 14.6 17.1 77.4 Example 7 Comparative 9.2 43.8 56.5 Example 8 Comparative 13.1 38.0 62.4 Example 9 Comparative 9.2 50.0 68.7 Example 10

Example 9

The oil produced in Example 5 was distilled within the cut range of 225° C. to 250° C., and cold flow properties were evaluated. The evaluation of this cold flow properties was made for a fraction obtained by distilling the oil to be evaluated, within the cut range of a specific temperature range, with an apparatus based on a crude oil distillation method shown in ASTM-D2892. The evaluation results are shown in Table 5.

The isoparaffin ratio as used herein was defined as the percent by mass of isoparaffin therein when the materials having 9 to 21 carbon number were taken as 100% by mass with gas chromatography. Further, the cloud point and pour point were measured according to JIS K2269. Furthermore, for the fraction obtained by distilling within the cut range of the specific temperature range, the 10% distillation temperature and 90% distillation temperature measured by a distillation test method shown in JIS K2254 are also shown in Table 5.

Example 10

The cold flow properties were measured in the same manner as in Example 9 with the exception that the cut range of distillation was changed to 250° C. to 275° C. The evaluation results are shown in Table 5.

Example 11

The cold flow properties were measured in the same manner as in Example 9 with the exception that the cut range of distillation was changed to 275° C. to 300° C. The evaluation results are shown in Table 5.

Example 12

The cold flow properties were measured in the same manner as in Example 9 with the exception that the cut range of distillation was changed to 300° C. to 325° C. The evaluation results are shown in Table 5.

Example 13

The cold flow properties were measured in the same manner as in Example 9 with the exception that the cut range of distillation was changed to 325° C. to 350° C. The evaluation results are shown in Table 5.

Comparative Example 11

In the FT process, a naphtha fraction, a kerosene fraction and a gas oil fraction are also generated concurrently with wax. These light fractions generated concurrently with wax-1 shown in Table 2 and FIG. 1 were hydrotreated using a catalyst of nickel supported on diatomaceous earth, thereby removing olefin and oxygen-containing compounds, and distillation was performed within the cut range of 225° C. to 250° C. to evaluate cold flow properties. The evaluation results are shown in Table 5.

Comparative Example 12

The cold flow properties were measured in the same manner as in Comparative Example 11 with the exception that the cut range of distillation was changed to 250° C. to 275° C. The evaluation results are shown in Table 5.

Comparative Example 13

The cold flow properties were measured in the same manner as in Comparative Example 11 with the exception that the cut range of distillation was changed to 275° C. to 300° C. The evaluation results are shown in Table 5.

Comparative Example 14

The cold flow properties were measured in the same manner as in Comparative Example 11 with the exception that the cut range of distillation was changed to 300° C. to 325° C. The evaluation results are shown in Table 5.

Comparative Example 15

The cold flow properties were measured in the same manner as in Comparative Example 11 with the exception that the cut range of distillation was changed to 325° C. to 350° C. The evaluation results are shown in Table 5.

TABLE 5 10% Distillation 90% Distillation Cloud Pour Isoparaffin Ratio Temperature Temperature point Point (% by Fuel Name (° C.) (° C.) (° C.) (° C.) mass) Example 9 226.0 233.5 −45 −42.5 86.69 Example 10 249.5 257.5 −31 −30.0 85.32 Example 11 271.5 278.0 −17 −15.0 80.91 Example 12 295.5 302.5 −6 −5.0 79.75 Example 13 316.5 323.0 5 5.0 77.34 Comparative 227.0 237.0 −10 −7.5 11.78 Example 11 Comparative 248.0 256.5 2 2.5 10.43 Example 12 Comparative 268.5 277.0 9 12.5 9.67 Example 13 Comparative 291.5 300.5 10 20.0 8.51 Example 14 Comparative 316.0 323.5 29 30.0 8.74 Example 15

Although the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications are possible without departing from the spirit and scope of the invention.

The invention is based on Japanese Patent Application (Toku-Gan 2004-090424) filed on Mar. 25, 2004, the whole of which is incorporated herein by reference.

INDUSTRIAL APPLICABILITY

According to the invention, heavy wax generated by the FT process is hydrotreated to perform cracking with the gasification rate restrained and to also increase an isomerization reaction which occurs at the same time, thereby being able to efficiently obtain a liquid fuel containing no sulfur and having good cold flow properties. 

1. A method for producing a hydrocarbon fuel oil, wherein wax generated by the Fischer-Tropsch synthesis and containing 50% or more by mass of normal paraffin having 7 to 100 carbon number is cracked and isomerized at a gasification rate of less than 10% by mass to an isoparaffin ratio in a fraction with 9 to 21 carbon number of 70% or more by mass, using a catalyst in which at least one kind of platinum group metal is contained on a support comprising zeolite as a main component in an amount of 0.01 to 10% by mass, in terms of metal, on a catalyst basis, at a hydrogen partial pressure of 2 to 20 MPa, at a temperature of 200 to 320° C., at a liquid hourly space velocity of 0.1 to 2 h⁻¹ and at a hydrogen/oil ratio of 100 to 2000 L/L.
 2. A method for producing a hydrocarbon fuel oil, wherein wax generated by the Fischer-Tropsch synthesis and containing 50% or more by mass of normal paraffin having 7 to 100 carbon number is cracked and isomerized at a gasification rate of less than 10% by mass to an isoparaffin ratio in a fraction with 9 to 21 carbon number of 70% or more by mass, using a catalyst in which at least one kind of platinum group metal is contained on a support comprising silica-alumina as a main component in an amount of 0.01 to 10% by mass in terms of metal on a catalyst basis, at a hydrogen partial pressure of 2 to 20 MPa, at a temperature of 350 to 400° C., at a liquid hourly space velocity of 0.1 to 2 h⁻¹ and at a hydrogen/oil ratio of 100 to 2000 L/L. 